Belted Kingfishers (Megaceryle alcyon) are widely distributed across aquatic environments in North America, but their behavior in marine habitats remains understudied, especially during the post-fledging period. We recorded daily activity budgets of adult and fledgling Belted Kingfishers on San Juan Island, Washington, and investigated the effects of tides and age class on feeding behaviors. Feeding attempt rate was highest at high tide, but strike success was highest at low tide. Adults foraged more successfully than juveniles and caught fish almost twice as large, consistent with juvenile inexperience during the post-fledging period. Strike success rates also varied between study sites for both adults and juveniles, potentially reflecting habitat quality. These results improve our understanding of how Belted Kingfishers behave in marine environments, and to our knowledge provide the first study of marine Belted Kingfishers during the post-fledging period. Follow-up studies quantifying prey availability and comparing seasonal behaviors of kingfishers in freshwater and marine habitats may help clarify the mechanisms behind the patterns we observed.